Which physical characteristic is NOT typically used in biometric verification?

Eye color is not typically used in biometric verification because it is not unique enough to reliably identify individuals. While eye color can vary significantly among different individuals, many people may share the same eye color, which reduces its effectiveness as a biometric identifier.

In contrast, fingerprints, facial recognition, and hand geometry are established biometric methods that rely on unique physical traits. Fingerprints are known for their individual variability, as no two fingerprints are ever identical. Facial recognition leverages specific facial features and their proportions to create a digital representation of a face, ensuring a higher level of certainty when identifying a person. Hand geometry measures the physical characteristics of a person's hand, including its size and shape, which are also distinct for each individual.

This combination of uniqueness and reliability makes fingerprints, facial recognition, and hand geometry appropriate choices for biometric verification, whereas eye color does not meet those criteria.